You can tell how young you still are by counting the number of baseball players older than you in a Topps baseball card set. I pulled all of the 1970's-born players from the 2015 Topps base set and arrange them in order from oldest to youngest. I found a total of 42 Topps cards featuring players born the 1970's--only 20 of which are still older than me. The countdown of '70s-born players has begun, with at least two of the 42 cards listed below featuring players that have already retired (Jeter and Konerko).
It was less than two years ago that we still had a '60s-born player in the major leagues by the name Mariano Rivera. Jamie Moyer was another '60s-born player that lasted until only three years ago. The last of the '50s-born players was Julio Franco only eight years ago. When I first started collecting baseball cards in 1987, the majority of major leaguers were born in the '40s, '50s, and early '60s. I remember Phil Niekro being the last of the '30s born players still in the game.
When I started back up collecting baseball cards after a 10-year hiatus, I remember the significance of being older than quite a few major leaguers that had entered the game in the mid-90's. Now, we are counting down the '70s-born major leaguers with the following 42 cards.